The present invention relates to apparatuses and methods for ballistic-impact armor structure and specifically precision formed container armor structure and methodology for making such structure and, more particularly to a lightweight and, more particularly to a lightweight ceramic-based integral armor made of cross-pellets and used for dissipating kinetic energy from ballistic projectiles, the armor having high fracture toughness.
During the last few decades, efforts have been made to produce ceramic-based armors which will be lower in mass than metals and thus be potentially more suitable for applications where weight is of significant importance, for example aircraft armor and armor for the human body. Some of these efforts have looked towards silicon carbide as a potential candidate for such applications whereas others have used fiber-reinforced ceramic materials.
Ballistic resistant armor is used in many applications including, for example, protection of vehicles and persons from ballistic threats. Body armor to be worn on a person for protection from, for example, ballistic threats, has been available for several decades. In general, body armor protects vital parts of the human torso against penetration and severe blunt trauma from ballistic projectiles. In the development of body armor, there is a continuing effort to develop lighter, stronger, thinner, and more durable armor.
Ballistic resistant armor is used in many applications including, for example, protection of vehicles and persons from ballistic threats. Body armor to be worn on a person for protection from, for example, ballistic threats, has been available for several decades. In general, body armor protects vital parts of the human torso against penetration and severe blunt trauma from ballistic projectiles. In the development of body armor, there is a continuing effort to develop lighter, stronger, thinner, and more durable armor.
Ceramic materials have long been considered for use in the fabrication of armor components because ceramic materials have a high hardness, are potentially capable of withstanding armor-piercing projectiles, and are relatively lightweight. However, the use of ceramic materials in armor applications has been limited by the low impact resistance of these materials, which results from ceramic's brittleness and lack of toughness. Indeed, one of the significant drawbacks to the use of ceramic materials in armor applications is that they lack repeat hit capability. In other words, ceramic materials tend to disintegrate upon the first hit and cease to be useful when subjected to multiple projectiles. For a more effective utilization of ceramic materials in armor applications, it is necessary to improve the impact resistance of this class of materials.
Desired minor protection levels can usually be obtained if weight is not a consideration. However, in many armor applications, there is a premium put on weight. Some areas of application where lightweight armor are important include ground combat and tactical vehicles, portable hardened shelters, helicopters, and various other aircraft used by the Army and the other Services. Another example of an armor application in need of reduced weight is personnel body armor worn by soldiers and law enforcement personnel.
State-of-the-art integral armor designs typically work by assembling arrays of ballistic grade ceramic tiles within an encasement of polymer composite plating. Such an armor system will erode and shatter projectiles, including armor-piercing projectiles, thus creating effective protection at reduced weight. Various designs are in current use over a range of applications. Substantial development efforts are ongoing with this type of armor, as it is known that its full capabilities are not being utilized. For example, there is a large body of information which shows that confining the ceramics results in an increase in penetration resistance.
The recent war in Iraq has heightened the need for ballistic armor. Military vehicles, in particular, are vulnerable to higher-potency weapons such as rocket-launched grenades and other projectiles. Military personnel want lightweight, fast and maneuverable vehicles, but they also want vehicle occupants to be fully protected. Ballistic steel armor plates, while relatively inexpensive, add thousands of pounds to a vehicle, many of which were not designed to carry such loads. This has resulted in numerous engine and transmission failures as well as problems with vehicle suspensions and brakes. The additional weight reduces fuel efficiency and makes it impossible to carry additional personnel in the vehicle in case of emergency. For these reasons, designers are beginning to adopt more lightweight composite armor across the board for military and tactical vehicles.
Multiple hits are a serious problem with ceramic-based armors. Armor-grade ceramics are extremely hard, brittle materials, and after one impact of sufficient energy, the previously monolithic ceramic will fracture extensively, leaving many smaller pieces and a reduced ability to protect against subsequent hits in the same vicinity. Further, when the impact is at sufficient energy and velocity, collateral damage typically occurs to the neighboring ceramic tiles. Schade, et al. (U.S. Pat. No. 5,705,764) uses a combination of polymers and polymer composites to encase the ceramic tiles in a soft surround to isolate the tiles from one another, reducing collateral damage.
Prior art armor or methods and apparatuses for such armor are described in U.S. Pat. Nos. 5,763,813; 5,972,819; 6,289,781; 6,112,635; 6,203,908; and 6,408,734 and in WO-A-9815796, U.S. Pat. Nos. 4,836,084, 4,868,040 and 4,529,640, British Patents 1,081,464; 1,352,418; 2,272,272, and in U.S. Pat. No. 4,061,815, the relevant teachings of which are incorporated herein by reference.
Examples of problems with existing composite materials and products made from the materials can include high weight, high cost of the materials, high manufacturing costs, and long manufacturing times. Additional examples of problems have included insufficient heat transfer resistance, poor acoustic properties, poor chemical resistance, poor moisture or water resistance, and inferior electrical properties. Existing composite materials have also been proven marginally cost effective for use as structural members or high strength materials. Desired material properties which have been insufficiently addressed by existing composite materials, include, for example, high strength to weight ratios, hot and cold insulation, high impact and compressive resistance, high flex modulus/stiffness, low specific gravity, chemical stability, sandability, formability, machineability, acoustics, reduced dielectric constant, non-combustible, water resistance, reduced warpage and shrinkage, and the ability to adhere or attach to other materials via conventional hardware or glues. Furthermore, existing composite materials insufficiently combine various desired material properties together into a single material.
In the event cross-pellets bodies are distanced one from another to have them still retain their full ballistic resistance capabilities, in certain prior art armor it is known to add an “ear” or a pin-like protrusion to the ceramic body which acts to occupy the valley space and slow or erode the penetrating projectile or fragment. However, this adds to the complexity and cost of manufacture.
None of the prior art ceramic armors produced so far are entirely satisfactory, and the search has gone on for processes for producing more effective ceramic armors.
An incoming projectile may contact a pellet array in one of three ways: 1. Center contact. The impact allows the full volume of the pellet to participate in stopping the projectile, which cannot penetrate without pulverizing the whole pellet, an energy-intensive task. 2. Flank contact. The impact causes projectile yaw, thus making projectile arrest easier, as a larger frontal area is contacted, and not only the sharp nose of the projectile. The projectile is deflected sideways and needs to form for itself a large aperture to penetrate, thus allowing the armor to absorb the projectile energy. 3. Valley contact. The projectile is jammed, usually between the flanks of three pellets, all of which participate in projectile arrest. The high side forces applied to the pellets is resisted by the pellets adjacent thereto as held by the substrate or plate, and penetration is prevented.
There are four main considerations concerning protective armor panels. The first consideration is weight. Protective armor for heavy but mobile military equipment, such as tanks and large ships, is known. Such armor usually comprises a thick layer of alloy steel, which is intended to provide protection against heavy and explosive projectiles. However, reduction of weight of armor, even in heavy equipment, is an advantage since it reduces the strain on all the components of the vehicle. Furthermore, such armor is quite unsuitable for light vehicles such as automobiles, jeeps, light boats, or aircraft, whose performance is compromised by steel panels having a thickness of more than a few millimeters, since each millimeter of steel adds a weight factor of 7.8 kg/m2.
Armor for light vehicles is expected to prevent penetration of bullets of any type, even when impacting at a speed in the range of 700 to 1000 meters per second. However, due to weight constraints it is difficult to protect light vehicles from high caliber armor-piercing projectiles, e.g. of 12.7 and 14.5 mm, since the weight of standard armor to withstand such projectile is such as to impede the mobility and performance of such vehicles.
A second consideration is cost. Overly complex armor arrangements, particularly those depending entirely on composite materials, can be responsible for a notable proportion of the total vehicle cost, and can make its manufacture non-profitable.
A third consideration in armor design is compactness. A thick armor panel, including air spaces between its various layers, increases the target profile of the vehicle. In the case of civilian retrofitted armored automobiles which are outfitted with internal armor, there is simply no room for a thick panel in most of the areas requiring protection.
A fourth consideration relates to ceramic plates used for personal and light vehicle armor, which plates have been found to be vulnerable to damage from mechanical impacts caused by rocks, falls, etc.
In response to ever-increasing anti-armor threats, improvements are warranted in the field of blast and fragment protection from explosive devices as well as ballistic mitigation.
There is a compelling need for better armor including armor made from improved materials, including lighter weight, lower cost, lower manufacturing costs, structural strength, and other properties.